Hybrid light redirecting and light diffusing constructions

ABSTRACT

Solar light redirecting glazing units include light redirecting and light diffusing constructions. The solar light redirecting glazing units may include a glazing substrate, a visible light diffusing layer, and a light redirecting layer oriented such that incoming solar light contacts the visible light diffusing layer before contacting the light redirecting layer. The solar light redirecting glazing units may include a glazing substrate, a patterned visible light diffusing layer, and a light redirecting layer. The solar light redirecting glazing units may include two glazing substrates separated by an intervening space with a solar light redirecting layer disposed on one glazing substrate, and a visible light diffusing layer disposed on the other glazing substrate.

RELATED CASES

This application is a continuation application of U.S. Ser. No.14/008,372, filed on Mar. 12, 2012 as a US 371 -PCT/US2012/028693, nowallowed, which claims priority to U.S. Provisional Application No.61/469,147, Mar. 30, 2011.

FIELD OF THE DISCLOSURE

This disclosure relates generally to light redirecting constructions,especially solar light redirecting glazing units.

BACKGROUND

A variety of approaches are used to reduce energy consumption inbuildings. Among the approaches being considered and applied is the moreefficient use of sunlight to provide lighting inside buildings. Onetechnique for supplying light inside of buildings, such as in offices,etc. is the redirection of incoming sunlight. Because sunlight enterswindows at a downward angle, much of this light is not useful inilluminating a room. However, if the incoming downward light rays can beredirected upward such that they strike the ceiling, the light can bemore usefully employed in lighting the room.

A variety of articles have been developed to redirect sunlight toprovide illumination within rooms. A light deflecting panel is describedin U.S. Pat. No. 4,989,952 (Edmonds). These panels are prepared bymaking a series of parallel cuts in a sheet of transparent solidmaterial with a laser cutting tool. Examples of daylighting filmsinclude European Patent No. EP 0753121 and U.S. Pat. No. 6,616,285 (bothto Milner) which describe optical components that include an opticallytransparent body with a plurality of cavities. Another daylighting filmis described in U.S. Pat. No. 4,557,565 (Ruck et al.), which describes alight deflecting panel or plate which is formed of a plurality ofparallel identically spaced apart triangular ribs on one face. Examplesof films that have a plurality of prism structures are described in USPatent Publication No. 2008/0291541 (Padiyath et al.) and pending U.S.Patent Applications: Ser. No. 61/287,360, titled “Light RedirectingConstructions” filed Dec. 17, 2009 (Padiyath et al.), and Ser. No.61/287,354, titled “Light Redirecting Film Laminate” filed Dec. 17, 2009(Padiyath et al.).

A number of articles have been developed to scatter or diffuse light. InU.S. Pat. No. 6,608,722 (Cowan et al.), a diffuser is disclosed thattransmits or reflects incident light into a specific range of angles.The diffuser consists of two parts, the first part diffracts or reflectslight into a specific offset angle, the second part uniformly scattersthe light through a range of angles. In U.S. Pat. No. 5,534,386(Petersen et al.), a homogenizer for incident light includes a sheet ofembossable material including one micro-sculpted surface reliefstructure that controls the direction in which light propogates andhomogenizes light with directionality. U.S. Pat. No. 6,613,402 (Chou etal.) disclosed a rear projection screen assembly that includes adiffuser and a polarizer. The PCT Publication No. WO 00/10929 (Savant)discloses a surface light shaping diffuser by embossing or molding lightshaping structures onto a high quality optical glass. Particles havebeen used to scatter or diffuse light. US Patent Publication No.2008/0182958 (Lafleur et al.) describes light scattering polymerparticles that have a different refractive index at the center of theparticle than at the shell of the particle, and also disclosesdispersing the particles in a polymeric matrix. A number of referencesdescribe light diffusing or light scattering films that compriseparticles dispersed within a matrix. In U.S. Pat. No. 5,237,004 (Wu etal.) the matrix is a thermoplastic or thermoset polymer composition, inPCT Publication Nos. WO 97/01610 (Goetz et al.) and WO 2010/033571(Sherman et al.) the matrix is a pressure sensitive adhesive, and in PCTPublication No. WO 2008/144217 (Padiyath et al.) a light diffusing solarcontrol film includes a multi-layer film that transmits visible lightand reflects infrared light, and a light diffusing layer or surface. PCTPublication No. WO 2010/0297406 (Schaffer et al.) describes a lightdiffusing adhesive that includes an adhesive matrix and a blockcopolymer that forms light diffusing microdomains within the adhesivematrix. PCT Publication No. WO 2005/005162 (Hayashi et al.) describes ashading decorative sheet that includes a thermoplastic resin film with adecorative layer provided on its front face, where the decorativepattern has a gradation pattern in at least one direction.

SUMMARY

Disclosed herein are hybrid light redirecting and light diffusingconstructions. These light redirecting and light diffusing constructionscomprise solar redirecting glazing units. In some embodiments, the solarlight redirecting glazing units comprise a first glazing substrate, avisible light diffusing layer disposed on the first glazing substrate,and a light redirecting layer adjacent to the visible light diffusinglayer. The light redirecting layer comprises a major surface forming aplurality of prism structures. The visible light diffusing layer andlight redirecting layer are oriented such that incoming solar lightcontacts the visible light diffusing layer before contacting the lightredirecting layer.

In other embodiments, the solar light redirecting glazing units comprisea first glazing substrate, a patterned visible light diffusing layer,and a light redirecting layer adjacent to the visible light diffusinglayer. The light redirecting layer comprises a major surface forming aplurality of prism structures.

In still other embodiments, the solar light redirecting glazing unitscomprise a first glazing substrate comprising a first major surface anda second major surface, a solar light redirecting layer disposed on thefirst major surface of the first glazing substrate, a second glazingsubstrate comprising a first major surface and a second major surface, avisible light diffusing layer disposed on the first major surface of thesecond glazing substrate, and an intervening space between the solarlight redirecting layer and the visible light diffusing layer. The solarlight redirecting layer comprises a major surface forming a plurality ofprism structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-sectional view of a light redirecting prismstructure construction of some embodiments of this disclosure.

FIG. 2 shows a cross-sectional view of a light redirecting prismstructure construction of some embodiments of this disclosure.

FIG. 3 shows a cross-sectional view of a light redirecting prismstructure construction of some embodiments of this disclosure.

FIG. 4 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

FIG. 5 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

FIG. 6 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

FIG. 7 shows a cross-sectional view of a patterned hybrid lightredirecting and light diffusing construction of this disclosure.

FIG. 8 shows a cross-sectional view of a patterned hybrid lightredirecting and light diffusing construction of this disclosure.

FIG. 9 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

FIG. 10 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

FIG. 11 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

FIG. 12 shows a cross-sectional view of a hybrid light redirecting andlight diffusing construction of this disclosure.

The figures are not necessarily to scale. Like numbers used in thefigures refer to like components. However, it will be understood thatthe use of a number to refer to a component in a given figure is notintended to limit the component in another figure labeled with the samenumber.

DETAILED DESCRIPTION

Windows and similar constructions are used to provide natural sunlightto rooms, corridors, and the like, in buildings. However, the angle thatnatural sunlight falls upon windows is such that typically the light maynot penetrate far into the room or corridor. Additionally, since theincoming light may be unpleasantly strong near the window, users sittingnear the window may be induced to close shutters, blinds or curtains andthus eliminate this potential source of room illumination. Thereforeconstructions that can redirect sunlight from the normal incident angleto a direction towards the ceiling of a room, corridor, or other indoorspace would be desirable.

Another issue with the increased use of natural lighting is the presenceof glare. Glare is a commonly encountered phenomenon, experiencedwhenever sunlight is present. Glare can be defined as the contrastlowering effect of stray light in a visual scene. Glare can be dividedinto two types: discomfort glare and disability glare. Discomfort glarerefers to the sensation one experiences when the overall illumination istoo bright, for example on a snowy field under a bright sun. Disabilityglare refers to the reduced visibility of a target due to the presenceof a light source elsewhere in the field. It occurs when light from aglare source is scattered by the ocular media. This scattered lightforms a veil of luminance which reduces the contrast and thus thevisibility of the target. Both of these types of glare are an issue withwindows that use natural light to illuminate a room, office, or otherindoor space. As described above for incoming light that is unpleasantlystrong near the window, glare can also be eliminated through the use ofshutters, blinds or curtains and the like, but such methods reduce oreliminate the desirable natural lighting. It is desirable to reduce oreliminate glare without completely blocking the transmission of visiblelight.

The use of daylight redirecting films on windows to direct light towardsthe ceiling of a room, corridor or other indoor space to enhance thenatural lighting in the room, corridor or other indoor space canactually increase the issues with glare, since at least some of theincoming light is also directed downward into the room instead ofupwards toward the ceiling. This effect can be minimized through thedesign of the light redirecting elements of the film such as isdescribed in the pending U.S. Patent Applications: Ser. No 61/287,360,titled “Light Redirecting Constructions” filed Dec. 17, 2009 (Padiyathet al.), and Ser. No. 61/287,354, titled “Light Redirecting FilmLaminate” filed Dec. 17, 2009 (Padiyath et al.). However, even withthese techniques, some light can be directed into the room to contributeto glare. Additionally, since the light redirecting elements typicallyare light refracting prisms, some splitting of the incoming whitesunlight into its component colors can occur. This splitting intocomponent colors is not desirable.

Therefore, glazing constructions are desirable that include the featuresof redirection of incoming sunlight towards the ceiling of a room,corridor or other indoor space without increasing the glare or causingthe incoming sunlight to be split into the component colors. Thesedesirable outcomes may be achieved through the use of a hybrid glazingconstruction that comprises both a light redirecting element and avisible light diffusion element. These hybrid constructions may take avariety of different forms such as a multilayer film article or asseparate film or substrate layers, and the constructions may beconfigured in a variety of different ways.

The glazing constructions, regardless of their configuration, generallyhave a desirable balance of optical properties, such as transmission ofvisible light, haze and clarity. Generally it is desirable to have avisible light transmission (% T) of at least 50%. In some embodiments,the % T is 60%, 70%, 80%, 85%, 90%, or even 95%. The % T is impacted bya variety of factors (such as the absorption, refractive index andsurface topography of the materials used) including the level of haze inthe glazing construction, because haze measures the amount of light thatis scattered. Generally, it is desirable that the glazing constructionshave a haze value of at least 10%. In some embodiments, the haze is atleast 15%, at least 20%, at least 30%, or even at least 40%. Clarity,while it is a different parameter than haze, it is not independent fromhaze. For example, a construction that has a relatively high haze valuewill have a clarity value that is impacted by the relatively high haze.Generally it is desirable that the glazing constructions have a clarityvalue in the range of 10-99%. Transmission, haze and clarity will bediscussed further below and methods for measuring them are described inthe Examples section.

In one embodiment of this disclosure, the hybrid construction comprisesa glazing substrate, a visible light diffusing layer disposed on thefirst glazing substrate, and a light redirecting layer adjacent to thevisible light diffusing layer. The visible light diffusing layer andlight redirecting layer are oriented such that incoming solar lightcontacts the visible light diffusing layer before contacting the lightredirecting layer. There are certain advantages to this orientation ofelements. For example, having the incoming sunlight contact thediffusing layer cause scattered light to contact the light redirectinglayer to provide the desirable feature described above of reducing theglare and color formation of the redirected light. An additionaldesirable feature achieved with this orientation of elements is that thescattering of all incoming light that contacts the diffusing layerreduces the glare even of light that does not contact the lightredirecting layer. Incoming light that does not contact the lightredirecting layer can cause normal glare. The incoming light may notcontact the light redirecting layer either because it is an incomingangle that does not permit it to be redirected, or because the incominglight is contacting a portion of the window that does not contain theredirecting layer (it may be desirable to have the light redirectinglayer on only a portion of a window and the light redirecting layer maybe in a pattern, i.e. not a continuous layer). The light diffusing layerand the light redirecting layer may be laminated together to form acomposite multilayer construction or the layers may be separatearticles. Additional layers may also be present in the hybridconstruction.

In other embodiments of this disclosure, the hybrid constructioncomprises a first glazing substrate, a patterned visible light diffusinglayer, and a light redirecting layer adjacent to the visible lightdiffusing layer. The patterned visible light diffusing layer and lightredirecting layer adjacent to the visible light diffusing layer maycomprise a multilayer light redirecting film, or they may be separatelayers. The light diffusing layer and the light redirecting layer may beany orientation to the glazing substrate. The use of a patterned visiblelight diffusing layer provides the advantageous properties describedabove, coupled with the need to use fewer diffusive elements. This notonly can assist in making the manufacturing less expensive, it can beaesthetically more appealing to have less of the window surfacediffusive to visible light. For example, with a home or office window, aviewer that looks through a visible light diffusing element willgenerally have a hazy view instead of the desired bright exterior view.

In still other embodiments of this disclosure, the hybrid constructioncomprises at least two glazing substrates with the diffusive layer andlight redirecting layer each disposed on one of the glazing substrates.In these embodiments, regardless of the relative orientation of thediffusive layer and the light redirecting layer, an intervening space ispresent between the diffusive layer and the light redirecting layer.This intervening space can be a vacuum, as is common in some glazingconstructions, or the space may contain air or other gas such asnitrogen or argon, for example.

Therefore, it is possible with the hybrid constructions of thisdisclosure to prepare glazing articles that are able to increase theamount of lighting within a room by redirecting sunlight towards theceiling without the undesirable features of increased glare or splittingof the sunlight into its component colors. The hybrid constructions canbe used, for example at window manufacturers or can be retrofitted toexisting windows. Additionally, embodiments of the hybrid constructionsof this disclosure are suitable for use with single pane windows, doublepane windows and even windows with more than two panes.

The term “adjacent” as used herein, when referring to two layers, meansthat the two layers are in proximity with one another with nointervening open space between them. They may be in direct contact withone another (e.g. laminated together) or there may be interveninglayers. Examples of two layers disposed on a substrate where layer 1 andlayer 2 are adjacent include the configurations: substrate/layer 1/layer2; and layer 1/substrate/layer 2.

The term “optical substrate” as used herein refers to substrates thatare at least optically transparent, may be optically clear and may alsoproduce additional optical effects. Examples of optical substratesinclude optical films and glazing substrates, such as glass plates.

The term “light diffusing” as used herein regarding substrates, such asglazing substrates, and films, such as optical films, refers tosubstrates or films that are designed to diffuse light. This lightdiffusion may be effected, for example, through the use of a texturedsurface of a substrate, or through other means such as incorporation oflight diffusing particles within the matrix of a film. While it is notedthat all optical articles can be considered to diffuse light to someextent, substrates and films that are optically transparent or opticallyclear are not considered to be “light diffusing” unless some lightdiffusing property is imparted to these substrates or films.

The term “optical film” as used herein refers to films that are at leastoptically transparent, may be optically clear and may also produceadditional optical effects. Examples of additional optical effectsinclude, for example, light diffusion, light polarization or reflectionof certain wavelengths of light.

The term “optically transparent” as used herein refers to films orconstructions that appear to be transparent to the naked human eye. Theterm “optically clear” as used herein refers to film or article that hasa high light transmittance over at least a portion of the visible lightspectrum (about 400 to about 700 nanometers), and that exhibits lowhaze. An optically clear material often has a luminous transmission ofat least about 90 percent and a haze of less than about 2 percent in the400 to 700 nm wavelength range. Both the luminous transmission and thehaze can be determined using, for example, the method of ASTM-D 1003-95.

The term “ordered arrangement” as used herein to describe a plurality ofstructures, refers to a regular, repeated pattern of structures.

The terms “point”, “side”, and “intersection” as used herein, have theirtypical geometric meanings.

The term “aspect ratio” as used herein when referring to a structureattached to a substrate, refers to the ratio of the greatest height ofthe structure above the substrate to the base of the structure that isattached to, or part of, the substrate.

The term “adhesive” as used herein refers to polymeric compositionsuseful to adhere together two adherends. Examples of adhesives arecurable adhesives, heat activated adhesives, and pressure sensitiveadhesives.

Curable adhesives are adhesives that contain a curable reaction mixturewhich cures to form an adhesive bond. Unlike heat activated adhesives(removable upon the application of heat) and pressure sensitiveadhesives, curable adhesives are generally not removable after curingand are intended to form a permanent bond between two adherends.

Heat activated adhesives are non-tacky at room temperature but becometacky and capable of bonding to a substrate at elevated temperatures.These adhesives usually have a glass transition temperature (T_(g)) ormelting point (T_(m)) above room temperature. When the temperature iselevated above the T_(g) or T_(m), the storage modulus usually decreasesand the adhesive becomes tacky.

Pressure sensitive adhesive compositions are well known to those ofordinary skill in the art to possess at room temperature propertiesincluding the following: (1) aggressive and permanent tack, (2)adherence with no more than finger pressure, (3) sufficient ability tohold onto an adherend, and (4) sufficient cohesive strength to becleanly removable from the adherend. Materials that have been found tofunction well as pressure sensitive adhesives are polymers designed andformulated to exhibit the requisite viscoelastic properties resulting ina desired balance of tack, peel adhesion, and shear holding power.Obtaining the proper balance of properties is not a simple process.

As used herein, the term “microstructure” means the configuration offeatures wherein at least 2 dimensions of the features are microscopic.The topical and/or cross-sectional view of the features must bemicroscopic.

As used herein, the term “microscopic” refers to features of smallenough dimension so as to require an optic aid to the naked eye whenviewed from any plane of view to determine its shape. One criterion isfound in Modern Optic Engineering by W. J. Smith, McGraw-Hill, 1966,pages 104-105 whereby visual acuity, “ . . . is defined and measured interms of the angular size of the smallest character that can berecognized.” Normal visual acuity is considered to be when the smallestrecognizable letter subtends an angular height of 5 minutes of arc onthe retina. At typical working distance of 250 mm (10 inches), thisyields a lateral dimension of 0.36 mm (0.0145 inch) for this object.

In one embodiment of this disclosure, the hybrid construction comprisesa first glazing substrate, a visible light diffusing layer disposed onthe first glazing substrate, and a light redirecting layer adjacent tothe visible light diffusing layer. The visible light diffusing layer andlight redirecting layer are oriented such that incoming solar lightcontacts the visible light diffusing layer before contacting the lightredirecting layer.

There are certain advantages to this orientation of elements. Forexample, having the incoming sunlight contact the diffusing layer causescattered light to contact the light redirecting layer to provide thedesirable feature described above of reducing the glare and colorformation of the redirected light. An additional desirable featureachieved with this orientation of elements is that the scattering of allincoming light that contacts the diffusing layer reduces the glare evenof light that does not contact the light redirecting layer. Incominglight that does not contact the light redirecting layer can cause normalglare. The incoming light may not contact the light redirecting layereither because it is an incoming angle that does not permit it to beredirected, or because the incoming light is contacting a portion of thewindow that does not contain the redirecting layer (it may be desirableto have the light redirecting layer on only a portion of a window andthe light redirecting layer may be in a pattern, i.e. not a continuouslayer). The light diffusing layer and the light redirecting layer may belaminated together to form a composite multilayer construction or thelayers may be separate articles. Additional layers may also be presentin the hybrid construction.

Examples of suitable additional layers that can be used include, forexample, low emissivity (Low-e) layers, infrared light rejecting layers,and color or tinting layers. Examples of Low-e layers are Low-e coatingswhich reflect mid to far infrared energy. There are two general types ofLow-e coatings: pyrolytic Low-e coatings, commonly referred to as “hardcoats” are applied during the manufacture of glass; Low-e coatingapplied in a vacuum process, commonly referred to as “soft coats” areapplied after the glass plate is manufactured. Low-e coatings, if usedon, for example, glazing substrates, are generally not present onglazing surfaces to which additional coatings or layers are disposed.For example, if the glazing substrate has a Low-e coating, the visiblelight diffusing layer and/or light redirecting layer are not attached tothe Low-e coated surface.

Examples of infrared light rejecting layers include a wide range ofpossible layers. Infrared light may be rejected by reflection of theinfrared light, by absorption of the infrared light, or by a combinationthereof. A variety of multi-layer films have been developed to reflectinfrared light while allowing the transmission of visible light.Examples of such multi-layer films include Fabry-Perot interferencefilters such as described in U.S. Pat. Nos. 4,799,745 and 6,007,901.Other examples are multi-layer polymeric optical films that have beendescribed in, for example, U.S. Pat. No. 3,610,724 (Rogers); U.S. Pat.No. 3,711,176 (Alfrey, Jr. et al.), U.S. Pat. No. 4,446,305 (Rogers etal.); U.S. Pat. No. 4,540,623 (Im et al.); U.S. Pat. No. 5,448,404(Schrenk et al.); U.S. Pat. No. 5,882,774 (Jonza et al.); U.S. Pat. No.6,045,894 (Jonza et al.); U.S. Pat. No. 6,531,230 (Weber et al.); PCTPublication WO 99/39224 (Ouderkirk et al.); and US Patent Publications2001/0022982 (Neavin et al.); and 2006/0154049 (Padiyath et al.). Insuch polymeric multi-layer optical films, polymer materials are usedpredominantly or exclusively in the makeup of the individual layers.Such films can be compatible with high volume manufacturing processes,and may be made in large sheets and roll goods.

Infrared light may also be rejected by the use of an infrared absorbinglayer instead of, or in conjunction with, an infrared light reflectinglayer. An example of such an infrared light absorbing layer is a layercomprising infrared absorbing nanoparticles dispersed within a curedpolymeric binder. In some embodiments, this infrared light absorbinglayer has a thickness in a range from 1 to 20 micrometers, or from 1 to10 micrometers, or from 1 to 5 micrometers. This infrared lightabsorbing layer can include a plurality of metal oxide nanoparticles. Apartial listing of metal oxide nanoparticles includes tin, antimony,indium and zinc oxides and doped oxides. In some embodiments, the metaloxide nanoparticles include, tin oxide, antimony oxide, indium oxide,indium doped tin oxide, antimony doped indium tin oxide, antinomy tinoxide, antimony doped tin oxide or mixtures thereof. In someembodiments, the metal oxide nanoparticles include tin oxide or dopedtin oxide and optionally further includes antimony oxide and/or indiumoxide. The polymeric binder layer includes infrared radiation absorbingnanoparticles dispersed through the polymeric binder layer. The infraredradiation absorbing nanoparticles may include any material thatpreferentially absorbs infrared radiation. Examples of suitablematerials include metal oxides such as tin, antimony, indium and zincoxides and doped oxides. In some instances, the metal oxidenanoparticles include, tin oxide, antimony oxide, indium oxide, indiumdoped tin oxide, antimony doped indium tin oxide, antinomy tin oxide,antimony doped tin oxide or mixtures thereof. In some embodiments, themetal oxide nanoparticles include antimony oxide (ATO) and/or indium tinoxide (ITO). In some cases, the infrared radiation absorbingnanoparticles may include or be made of lanthanum hexaboride, or LaB₆.

Optional additional layers may also include color or tinting layers.These may be applied to the glazing substrate or to other layers. Theselayers may be film layers or coatings.

As stated above, it may be desirable for the light diffusing layerand/or the light redirecting layer to cover only a portion of the firstglazing substrate. The first glazing substrate has a first major surfaceand a second major surface. Each of these surfaces has a surface areavalue. It may be desirable, therefore, for the light diffusing layerand/or the light redirecting layer to cover only a portion of thesurface area value of the surface to which it is adhered.

A wide variety of glazing substrates are suitable in the glazing unitsof this disclosure. In some embodiments, a single glazing substrate ispresent, in other embodiments multiple glazing substrates are present.In some embodiments the light diffusing and light redirecting hybridconstruction is attached to an exterior surface of a glazing substrate,and in other embodiments, the hybrid construction is located between twoglazing substrates.

Suitable glazing substrates are at least optically transparent, and maybe optically clear. Examples of suitable substrates include, forexample, windows. Windows may be made of a variety or different types ofglazing substrates such as a variety of glasses or from polymericmaterials such as polycarbonate or polymethyl methacrylate. In someembodiments, the window may also comprise additional layers ortreatments. Examples of additional layers include, for example,additional layers of film designed to provide tinting, shatterresistance and the like. Examples of additional treatments that may bepresent of windows include, for example, coatings or various types suchas hardcoats, and etchings such as decorative etchings.

In some embodiments, the glazing substrate is a single pane substrateand the light diffusing and light redirecting hybrid construction isattached to an exterior surface of the single pane glazing substrate. Aslong as the orientation is maintained in which incoming solar lightcontacts the light diffusing layer before encountering the lightredirecting layer, a wide variety of configurations of layers aresuitable. For example, the light diffusing layer may be disposed on theinterior surface of the glazing substrate, by which is meant the sidethat faces the inside of the building. The light redirecting layer maybe attached directly to the diffusing layer, or there may be additionaloptional layers intervening as long as these layers do not interferewith the function of the light redirecting layer. In other embodiments,the diffusing layer, light redirecting layer, and any optional layerscan be applied to the exterior surface of the glazing substrate, bywhich it is meant the side that faces the outside environment. In stillother embodiments, the diffusing layer may be disposed on the exteriorsurface of the glazing substrate and the light redirecting layer may bedisposed on the interior surface of the glazing substrate. In theseembodiments, the glazing substrate is between the diffusing layer andthe light redirecting layer.

In some embodiments, more than one glazing substrate is present. A widerange of different configurations are possible that include more thanone glazing substrate. For example, the glazing substrate may be treatedlike a single pane substrate since the two glazing substrates areadhered together to essentially form a thicker glazing substrate. Oftenthe two panes or glazing are held together with an adhesive such aspolyvinyl butyral, and may have a layer of film between the two panes toprovide shatter resistance (an example of this type of glazing is safetyglass such as used in automobile windshields). In these multiple glazingsubstrates, the configurations of light diffusing layer, lightredirecting layer, and optional additional layers is the same asdescribed above.

In other double pane glazings, the two panes of glazing are parallel toeach other and are separated by a space. In some insulated windows, thespace is evacuated to provide a “dead space” between the two panes ofglazing. In glazings of this type, the light diffusing layer and thelight redirecting layer are configured on the same glazing substrate inthe configurations described above for a single glazing substrate.

The hybrid construction also comprises a visible light diffusing layerdisposed on the first glazing substrate. A wide variety of lightdiffusing layers are suitable. In some embodiments, the light diffusinglayer comprises a light diffusing film or coating that is attached tothe first glazing substrate. In other embodiments, the light diffusinglayer comprises a textured surface or topography capable of scatteringlight, present on the surface of the first glazing substrate. In stillother embodiments, the light diffusing layer comprises a light diffusingsubstrate, such as a glazing substrate, that comprises a texturedsurface or topography capable of scattering light, present on thesurface of the light diffusing substrate or may contain light diffusingparticles either within the substrate matrix, or present as a surfacecoating within a cured binder matrix. In these embodiments, the lightdiffusing substrate is separate from the first glazing substrate.

In many embodiments, the light diffusing layer includes a lightdiffusing film or coating that is capable of providing bulk diffusion ofvisible light. These light diffusing films or coatings may also compriseadditional functionality besides the diffusion of light. For example,the coatings may be hard coats to provide resistance to scratching,marring or soiling or they may have adhesive properties. The films mayprovide light control properties such as infrared light reflection orphysical properties such as shatter resistance.

Typically, these films or coatings comprise light scattering particlesdispersed within a cured binder matrix. The light scattering particlesand the binder have different refractive indices. In many embodiments,the light scattering particles have a first refractive index and thebinder has a second refractive index and the second refractive index isat least a value of 0.05 different than the first refractive index. Insome embodiments, the light scattering particles have a first refractiveindex and the binder has a second refractive index and the secondrefractive index is at least a value of 0.1 different than the firstrefractive index. The light diffusing layer provides the hybridconstruction with a haze value of at least 10% or greater or at least30% or greater, or at least 50% or greater. Another property that can beused to measure the optical properties of the light diffusing layer isclarity. Typically, clarity is in the range of 10-99%. Clarity is also ameasure of the scattering of light and therefore layers that have arelatively high haze are also going to have their clarity affected. Hazeand clarity are measured according to ASTM D 1003-00. In someembodiments, the light diffusing layer provides the hybrid constructionwith a haze value range from 10% to 95%, or from 20% to 75%. Theparticles can be formed of any useful light scattering material and canhave any useful size and loading within the binder. In many embodiments,the particles have an approximate diameter in a range from 1 to 25micrometers and a refractive index in a range from 1.5 to 1.6.Illustrative light diffusing layers are described in U.S. Pat. No.6,163,402 (Chou et al.), and PCT Publication WO 2005/005162 (Hayashi etal.) which described illustrative printed light diffusing layers.

Examples of suitable diffusive films include members of the FASARA lineof films commercially available from 3M Company, St. Paul, Minn. Theoptical properties (Transmittance, Haze and Clarity) of some of thesefilms and the films on a glass plate are shown in Table A below. Theoptical properties were measured using a “HAZE-GARD PLUS” (BYK-Gardner,Columbia, Md.) according to test method ASTM D1003. In Table A, “FilmOnly” means just the FASARA film was measured, the other measurementswere made of laminates of the FASARA film on a glass plate.

TABLE A Film on 3 mm thick glass with Film Only film side towards lightSample Trans Haze Clarity Trans Haze Clarity FASARA Film (%) (%) (%) (%)(%) (%) SAN MARINO 68 100 15 56 100 18 LAUSANNE 92 42 54 88 40 54 MAT 9357 20 89 56 19 CRYSTAL i MILANO 77 93 30 70 90 31 FINE 93 42 33 90 41 33CRYSTAL

In some embodiments, the light diffusing layer binder is a curedpolymeric material that can function as a hardcoat. Suitable polymericbinders include the thermal and/or UV-polymerized (i.e., cured) productsof acrylate and/or methacrylate monomers. A suitable cured binder is thethermal and/or UV-polymerized product of a brominated, alkyl-substitutedphenyl acrylate or methacrylate (e.g., 4,6-dibromo-2-sec-butyl phenylacrylate), a methyl styrene monomer, a brominated epoxy diacrylate,2-phenoxyethyl acrylate, and a hexa-functional aromatic urethaneacrylate oligomer, as described in U.S. Pat. No. 6,355,754. While mosttypes of energy polymerizable telechelic monomers and oligomers areuseful for forming these polymeric binders, acrylates are preferredbecause of their high reactivity. The curable binder composition shouldbe of flowable viscosity that is low enough that air bubbles do notbecome entrapped in the composition. Reactive diluents can be mono- ordi-functional monomers such as, for example, SR-339, SR-256, SR-379,SR-395, SR-440, SR-506, CD-611, SR-212, SR-230, SR-238, and SR-247available from Sartomer Co., Exton, Pa. Typical useful oligomers andoligomeric blends include CN-120, CN-104, CN-115, CN-116, CN-117,CN-118, CN-119, CN-970A60, CN-972, CN-973A80, CN-975 available fromSartomer Co., Exton, Pa. and Ebecryl 1608, 3200, 3201, 3302, 3605, 3700,3701, 608, RDX-51027, 220, 9220, 4827, 4849, 6602, 6700-20T availablefrom Surface Specialties, Smyrna, Ga. Additionally, a multi-functionalcrosslinker can assist in providing a durable, high crosslink densitycomposite matrix. Examples of multifunctional monomers include SR-295,SR-444, SR-351, SR-399, SR-355, and SR-368 available from Sartomer Co.,Exton, Pa. and PETA-K, PETIA and TMPTA-N available from SurfaceSpecialties, Smyrna, Ga. Multi-functional monomers can be used ascrosslinking agents to increase the glass transition temperature of thebinder polymer that results from the polymerizing of the polymerizablecomposition. The light diffusing layer binder can form a hard resin orhardcoat. The term “hard resin” or “hardcoat” means that the resultingcured polymer exhibits an elongation at break of less than 50 or 40 or30 or 20 or 10 or 5 percent when evaluated according to the ASTMD-882-91 procedure. In some embodiments, the hard resin polymer canexhibit a tensile modulus of greater than 100 kpsi (6.89×10⁸ Pascals)when evaluated according to the ASTM D-882-91 procedure. In someembodiments, the hard resin polymer can exhibit a haze value of lessthan 10% or less than 5% when tested in a Taber abrader according toASTM D 1044-99 under a load of 500 g and 50 cycles (haze can be measuredwith Haze-Gard Plus, BYK-Gardner, Md., haze meter).

In some embodiments, the light diffusing layer binder is a curedpolymeric material that can function as an adhesive. These adhesivelayers can provide adhesion to bind together other layers while alsoproviding diffusion of light. These adhesive layers can be curablelayers or they can be pressure sensitive adhesive or heat activatedadhesive layers. Examples of pressure sensitive adhesive layers withlight diffusion properties include those described in PCT PublicationNos. WO 97/01610 (Goetz et al.) and WO 2010/033571 (Sherman et al.) andUS Patent Publication No. US 2010/0297406 (Schaffer et al.).

In some embodiments, the light diffusing layer is a light diffusingsurface on the first glazing substrate. The light diffusing surface maycomprise a textured surface or topography that is capable of scatteringlight (i.e., surface light diffusion) as light transmits through thelight diffusing surface. The textured surface or topography can beformed using any useful technique. In some embodiments, the texturedsurface is formed via embossing or erosion (e.g., sandblasting). Inother embodiments, the textured surface is formed via casting onto atextured master surface. The textured surface can be defined by aplurality of peaks and valleys that are randomly or non-randomly placedor formed along a surface. These peaks and valleys are effective todisperse or diffuse light that transmits through the light diffusingsurface. The light diffusing surface provides the hybrid constructionwith a haze value of at least 10% or greater or at least 30% or greater,or at least 50% or greater. Haze is measured according to ASTM D1003-00. In some embodiments, the light diffusing surface provides thehybrid construction with a haze value range from 10% to 95%, or from 20%to 75%.

In some embodiments, the light diffusing layer comprises a lightdiffusing substrate, such as a glazing substrate. The light diffusingsubstrate may comprise a textured surface or topography capable ofscattering light, present on the surface of the light diffusingsubstrate. In some embodiments, the light diffusing substrate maycomprise light diffusing particles within the substrate matrix. Examplesof light diffusing substrates that comprise light diffusing particleswith the substrate matrix include polycarbonate or polymethylmethacrylate substrates prepared with light diffusing particlesincorporated into the polycarbonate or polymethyl methacrylate orapplied as a coating to the substrate.

In embodiments where the light diffusing layer is a film, it may beadhered to the first glazing substrate in a variety of ways, such as byheat lamination or through the use of an adhesive layer. Heat laminationinvolves applying the light diffusing film to the glazing substrate andapplying heat and pressure to adhere the film to the glazing substratesurface. In many embodiments, it may be desirable to use an adhesivelayer to adhere the light diffusing layer to the first glazingsubstrate.

Examples of adhesives suitable for use as the adhesive layer include,for example, heat activated adhesives, pressure sensitive adhesives orcurable adhesives. Examples of suitable optically clear curableadhesives include those described in U.S. Pat. No. 6,887,917 (Yang etal.). Depending upon the nature of the adhesive, the adhesive coatingmay have a release liner attached to it to protect the adhesive coatingfrom premature adhesion to surfaces and from dirt and other debris whichcan adhere to the adhesive surface. The release liner typically remainsin place until the light redirecting laminate is to be attached to thesubstrate. Typically, a pressure sensitive adhesive is used.

A wide variety of pressure sensitive adhesive compositions are suitable.In some embodiments, the pressure sensitive adhesive is optically clear.The pressure sensitive adhesive component can be any material that haspressure sensitive adhesive properties. Additionally, the pressuresensitive adhesive component can be a single pressure sensitive adhesiveor the pressure sensitive adhesive can be a combination of two or morepressure sensitive adhesives.

Suitable pressure sensitive adhesives include, for example, those basedon natural rubbers, synthetic rubbers, styrene block copolymers,polyvinyl ethers, poly(meth)acrylates (including both acrylates andmethacrylates), polyolefins, silicones, or polyvinyl butyral.

The optically clear pressure sensitive adhesives may be(meth)acrylate-based pressure sensitive adhesives. Usefulalkyl(meth)acrylates (i.e., acrylic acid alkyl ester monomers) includelinear or branched monofunctional unsaturated acrylates or methacrylatesof non-tertiary alkyl alcohols, the alkyl groups of which have from 4 to14 and, in particular, from 4 to 12 carbon atoms. Poly(meth)acrylicpressure sensitive adhesives are derived from, for example, at least onealkyl(meth)acrylate ester monomer such as, for example, isooctylacrylate, isononyl acrylate, 2-methyl-butyl acrylate, 2-ethyl-n-hexylacrylate and n-butyl acrylate, isobutyl acrylate, hexyl acrylate,n-octyl acrylate, n-octyl methacrylate, n-nonyl acrylate, isoamylacrylate, n-decyl acrylate, isodecyl acrylate, isodecyl methacrylate,isobornyl acrylate, 4-methyl-2-pentyl acrylate and dodecyl acrylate; andat least one optional co-monomer component such as, for example,(meth)acrylic acid, vinyl acetate, N-vinyl pyrrolidone,(meth)acrylamide, a vinyl ester, a fumarate, a styrene macromer, alkylmaleates and alkyl fumarates (based, respectively, on maleic and fumaricacid), or combinations thereof.

In certain embodiments, the poly(meth)acrylic pressure sensitiveadhesive is derived from between about 0 and about 20 weight percent ofacrylic acid and between about 100 and about 80 weight percent of atleast one of isooctyl acrylate, 2-ethyl-hexyl acrylate or n-butylacrylate composition.

In some embodiments, the adhesive layer is at least partially formed ofpolyvinyl butyral. The polyvinyl butyral layer may be formed via knownaqueous or solvent-based acetalization process in which polyvinylalcohol is reacted with butyraldehyde in the presence of an acidiccatalyst. In some instances, the polyvinyl butyral layer may include orbe formed from polyvinyl butyral that is commercially available fromSolutia Incorporated, of St. Louis, Mo., under the trade name “BUTVAR”resin.

In some instances, the polyvinyl butyral layer may be produced by mixingresin and (optionally) plasticizer and extruding the mixed formulationthrough a sheet die. If a plasticizer is included, the polyvinyl butyralresin may include about 20 to 80 or perhaps about 25 to 60 parts ofplasticizer per hundred parts of resin. Examples of suitableplasticizers include esters of a polybasic acid or a polyhydric alcohol.Suitable plasticizers are triethylene glycol bis(2-ethylbutyrate),triethylene glycol di-(2-ethylhexanoate), triethylene glycoldiheptanoate, tetraethylene glycol diheptanoate, dihexyl adipate,dioctyl adipate, hexyl cyclohexyl adipate, mixtures of heptyl and nonyladipates, diisononyl adipate, heptylnonyl adipate, dibutyl sebacate,polymeric plasticizers such as the oil-modified sebacic alkyds, andmixtures of phosphates and adipates such as disclosed in U.S. Pat. No.3,841,890 and adipates such as disclosed in U.S. Pat. No. 4,144,217.

The adhesive layer may be crosslinked. The adhesives can be crosslinkedby heat, moisture or radiation, forming covalently crosslinked networkswhich modify the adhesive's flowing capabilities. Crosslinking agentscan be added to all types of adhesive formulations but, depending on thecoating and processing conditions, curing can be activated by thermal orradiation energy, or by moisture. In cases in which crosslinker additionis undesirable one can crosslink the adhesive if desired by exposure toan electron beam.

The degree of crosslinking can be controlled to meet specificperformance requirements. The adhesive can optionally further compriseone or more additives. Depending on the method of polymerization, thecoating method, the end use, etc., additives selected from the groupconsisting of initiators, fillers, plasticizers, tackifiers, chaintransfer agents, fibrous reinforcing agents, woven and non-wovenfabrics, foaming agents, antioxidants, stabilizers, fire retardants,viscosity enhancing agents, and mixtures thereof can be used.

In addition to being optically clear, the pressure sensitive adhesivemay have additional features that make it suitable for lamination tolarge substrates such as windows. Among these additional features istemporary removability. Temporarily removable adhesives are those withrelatively low initial adhesion, permitting temporary removability from,and repositionability on, a substrate, with a building of adhesion overtime to form a sufficiently strong bond. Examples of temporarilyremovable adhesives are described, for example in U.S. Pat. No.4,693,935 (Mazurek). Alternatively, or in addition, to being temporarilyremovable, the pressure sensitive adhesive layer may contain amicrostructured surface. This microstructured surface permits air egressas the adhesive is laminated to a substrate. For optical applications,typically, the adhesive will wet out the surface of the substrate andflow to a sufficient extent that the microstructures disappear over timeand therefore do not affect the optical properties of the adhesivelayer. A microstructured adhesive surface may be obtained by contactingthe adhesive surface to a microstructuring tool, such as a release linerwith a microstructured surface.

The pressure sensitive adhesive may be inherently tacky. If desired,tackifiers may be added to a base material to form the pressuresensitive adhesive. Useful tackifiers include, for example, rosin esterresins, aromatic hydrocarbon resins, aliphatic hydrocarbon resins, andterpene resins. Other materials can be added for special purposes,including, for example, oils, plasticizers, antioxidants, ultraviolet(“UV”) stabilizers, hydrogenated butyl rubber, pigments, curing agents,polymer additives, thickening agents, chain transfer agents and otheradditives provided that they do not reduce the optical clarity of thepressure sensitive adhesive. In some embodiments, the pressure sensitiveadhesive may contain a UV absorber (UVA) or hindered amine lightstabilizer (HALS). Suitable UVAs include, for example, benzotriazoleUVAs such as the compounds available from Ciba, Tarrytown, N.Y. asTINUVIN P, 213, 234, 326, 327, 328, 405 and 571. Suitable HALS includecompounds available from Ciba, Tarrytown, N.Y. as TINUVIN 123, 144, and292.

The hybrid construction also comprises a light redirecting layeradjacent to the visible light diffusing layer. As described above, thelight redirecting layer, depending upon the configuration of the glazingarticle, may be adhered to visible light diffusing layer, to the firstglazing substrate, or to some other optional layer intermediate betweenthe visible light diffusing layer, or the first glazing substrate andthe light redirecting layer. The light redirecting layer may be adheredto any of these layers by, for example an adhesive layer, such as theadhesive layers described above.

The light redirecting layer surface comprises an optical substrate witha microstructured surface. This microstructured surface comprises anordered arrangement of a plurality of prism structures. The orderedarrangement of prism structures can form an array of microstructures.The array can have a variety of elements. For example, the array can belinear (i.e. a series of parallel lines), sinusoidal (i.e. a series ofwavy lines), random, or combinations thereof. While a wide variety ofarrays are possible, it is desirable that the array elements arediscrete, i.e., that the array elements do not intersect or overlap. Insome embodiments, the prisms are symmetrical and in other embodimentsthe prisms are asymmetrical multi-sided refractive prisms.

Suitable symmetrical prism structures are described in US PatentPublication No. 2008/0291541 (Padiyath et al.). In some embodiments, afilling layer is disposed within cavities formed between adjacent prismstructures. In these embodiments, the filling layer has a refractiveindex value that is different than a refractive index value of the prismstructures. This difference can be a value of 0.05 or greater or 0.1 orgreater. The filling layer can be formed of any useful visible lighttransmitting material such as, for example, a polymer material.

In some embodiments, the filling layer is capable of being cleanlyremoved from the plurality of prism structures. For example, the hybridconstruction can be applied onto a glazing substrate and then thefilling layer can be removed to expose the prism structures. Thus, thefilling layer protects the prism structures until the hybridconstruction is applied and then can be removed, if desired. The term“cleanly” removed refers to leaving substantially no filling layerresidue on the prism structures and also leaving substantially no prismstructure residue on the filling layer. In some embodiments, the fillinglayer is used as a structure template to aid in forming the prismstructures.

The prism structures and/or filling layer can be formed of any usefulpolymerizable composition. In many embodiments, the prism structuresand/or filling layer are formed from different polymerizablecompositions. In some embodiments, the polymerizable composition isformed of monomers including mono-, di-, or higher functional monomers,and/or oligomers, and in some embodiments, those having a high index ofrefraction, for example, greater than about 1.4 or greater than about1.5. The monomers and/or oligomers may be polymerizable using UVradiation. Suitable materials include (meth)acrylates, halogenatedderivatives, telechelic derivatives, and the like, for example, thosedescribed in U.S. Pat. Nos. 4,568,445; 4,721,377; 4,812,032; 5,424,339;and 6,355,754. In some embodiments, the polymerizable compositionsinclude polyesters such as polyethylene terephthalate, polyethylenenaphthalate, copolyesters or polyester blends based on naphthalenedicarboxylic acids; polycarbonates; polystyrenes;styrene-acrylonitriles; cellulose acetates; polyether sulfones;poly(methyl)acrylates such as polymethylmethacrylate; polyurethanes;polyvinyl chloride; polycyclo-olefins; polyimides; glass; orcombinations or blends thereof. The polymerizable compositions may alsoinclude a naphthalate-containing multilayered optical film as describedin U.S. Pat. No. 6,111,696.

In some embodiments, the prism structures polymerizable composition isdescribed in U.S. Patent Publication No., 2005/0147838. Thispolymerizable composition includes a first monomer comprising a majorportion of 2-propenoic acid,(1-methylethylidene)bis-(2,6-dibromo-4,1-phenylene)oxy(2-hydroxy-3,1-propanediyl))ester;pentaerythritol tri(meth)acrylate; and phenoxyethyl(meth)acrylate.

In some embodiments, the prism structures are linear prism structures,or pyramidal prism structures. In some embodiments, the prism structuresare linear prism structures or non-linear or broken linear prismstructures. The prism structures redirect at least a portion of thevisible light incident upon the light redirecting layer. In manyembodiments, at least 50% of visible light incident upon the lightredirecting layer is redirected by the light redirecting layer. In manyembodiments, the plurality of prism structures cooperates to direct atleast a portion of incident light in substantially the same direction ordirections. This light redirecting effect is due to refraction at theprism surface interface.

The symmetrical prism structures may be regular sharp tip prismstructures, or they may have other useful configurations such as, forexample, shape tip, rounded tip, and/or truncated tip, as desired. Theprism structures can have a varying height, spatially varying pitch, orspatially varying facet angle, as desired. In some embodiments, theprism structures have a pitch and height in a range from 50 to 2000micrometers, or from 50 to 1000 micrometers.

In some embodiments, the microstructured surface comprises an orderedarrangement of a plurality of asymmetrical multi-sided refractiveprisms. Suitable asymmetrical multi-sided prism structures are describedin pending U.S. Patent Applications: Ser. No. 61/287,360, titled “LightRedirecting Constructions” filed Dec. 17, 2009 (Padiyath et al.), andSer. No. 61/287,354, titled “Light Redirecting Film Laminate” filed Dec.17, 2009 (Padiyath et al.). It can be desirable that the prisms beasymmetrical such that incoming incident solar light (which comes fromabove and is incident upon the film at an angle of from 15-80° from thedirection perpendicular to the substrate) is redirected upwards towardsthe ceiling of the room, but incoming light from below is not redirecteddownwards. An artifact of symmetrical structures is that the downwarddirected light could be visible to the observer, which is undesirable.

The plurality of asymmetrical multi-sided refractive prisms is designedto effectively redirect incoming solar light towards the ceiling of aroom which contains a window or other aperture containing the lightdirecting film. Typically, the asymmetrical multi-sided refractiveprisms comprise 3 or greater sides, more typically 4 or greater sides.The prisms may be viewed as an orderly array of protrusions arising fromthe surface of the optical film. Typically, the aspect ratio of theseprotrusions is 1 or greater, that is to say that the height of theprotrusion is at least as great as the width of the protrusion at thebase. In some embodiments, the height of the protrusions is at least 50micrometers. In some embodiments, the height of the protrusions is nomore than 250 micrometers. This means that the asymmetrical structurestypically protrude from 50 micrometers to 250 micrometers from the firstmajor surface of the optical substrate.

Exemplary asymmetrical light redirecting prism structure constructionsare shown in FIGS. 1-3. FIG. 1 shows light redirecting prism structureconstruction 100 which contains optical substrate 105 and the crosssection of a single prism 115. Prism 115 has 4 sides, side A which isadjacent to optical substrate 105, side B which is joined to side A,side C which is joined to side A, and side D which is joined to side Band side C.

Side B is angled in such a way that it produces total internalreflection to solar light rays incident upon the second major surface ofthe optical substrate. Solar light rays are incident from above thesecond major surface of the optical substrate and typically form anangle of from about 15-80° from perpendicular to the first major surfaceof the optical substrate depending upon the time of day, time of year,geographical location of the light redirecting construction, etc. Theincident light rays enter the prism 115 and are reflected from side B bythe phenomenon of total internal reflection. To achieve total internalreflection, it is desirable that side B not be perpendicular to side A,but be offset from perpendicular by angle θ as shown in FIG. 1. Theselection of the value for angle θ will depend upon a variety ofvariable features including, for example, the refractive index of thecomposition materials used to prepared the light management film, theproposed geographic location of use for the light management film, etcbut typically the value for angle θ is in the range 6-14° or even 6-12°.

Side C is joined to side A and connects side A to side D. It isdesirable that side A not be perpendicular to side A, but be offset fromperpendicular by angle α. The offset of angle α, among other features,aids in preventing light which exits prism 115 through side D fromentering an adjacent prism (not shown in FIG. 1). As with angle θ, theselection of the value for angle α depends upon a variety of variablefeatures, including the closeness of adjacent prisms, the nature andsize of side D, etc. Typically, angle α is in the range 5-25° or even9-25°.

Side D is the side of the prism from which the redirected light raysexit the prism. In FIG. 1 side D is shown as a single side but side Dmay comprise a series of sides. Also, in FIG. 1 side D is shown as acurved side, but side D need not be curved in all embodiments. Lightrays that are reflected from side B are redirected by side D to adirection useful for improving the indirect lighting of a room. By thisit is meant that the light rays reflected from side D are redirectedeither perpendicular to side A or at an angle away from perpendicularand towards the ceiling of the room.

In some embodiments, side C may be curved, side D may be curved, or thecombination of sides C and D may form a single continuously curved side.In other embodiments, side C or D or C and D taken together comprises aseries of sides, wherein the series of sides comprises a structuredsurface. The structured surface may be regular or irregular, i.e., thestructures may form regular patterns or random patterns and may beuniform or the structures may be different. These structures, since theyare substructures on a microstructure, are typically very small.Typically, each dimension of these structures (height, width and length)is smaller than the dimension of side A.

FIG. 2 shows another embodiment of a light redirecting prism structureconstruction. In FIG. 2, light directing construction 200 containsoptical substrate 205 and the cross section of a single prism 215. Prism215 has 4 sides, side A which is adjacent to optical substrate 205, sideB which is joined to side A, side C which is joined to side A, and sideD which is joined to side B and side C. Side D comprises sub-side D1.Sub-side D1 is joined to side B by a point. This point provides a pointof contact with a glazing substrate or an optional cover film (theglazing substrate or optional cover film are not shown in FIG. 2). Theangles θ and α are as defined in FIG. 1.

FIG. 3 shows another embodiment of a light redirecting prism structureconstruction. In FIG. 3, light directing construction 300 containsoptical substrate 305 and the cross section of a single prism 315. Prism315 has 4 sides, side A which is adjacent to film 305, side B which isjoined to side A, side C which is joined to side A, and side D which isjoined to side B and side C. Side D comprises sub-side D2. Sub-side D2is joined to side B and is designed to form a bonding zone with aglazing substrate or cover film (the glazing substrate or cover film isnot shown in FIG. 3). The angles θ and α are as defined in FIG. 1.

The entire surface of the light redirecting layer may containmicrostructures, or the microstructures may be present on only a portionof a first surface of the light redirecting layer. This is particularlytrue in instances when the hybrid construction is attached to a glazingarticle that is incorporated into a glazing article in, for example, awindow. It may not be necessary or desirable for the entire surface ofthe glazing substrate to contain a microstructured surface in order toproduce the desirable light redirection effect.

The visible light diffusing layer and the light redirecting layer areadjacent to each other. In some embodiments, the visible light diffusinglayer and the light redirecting layer are adhered to one another to forma composite light redirecting construction. A wide variety of suchcomposite constructions are possible. For example, in some embodiments,a light diffusing layer may be incorporated into the surface of thefirst glazing substrate with a light redirecting film adhered to thissurface. In other embodiments, the visible light diffusing layer and thelight redirecting layer may both be polymeric films that are laminatedto each other and adhered to the first glazing substrate. The compositeconstructions may be adhered to each other and to the first glazingsubstrate through the use of an adhesive layer, such as those describedabove.

Some specific embodiments of hybrid constructions comprising a firstglazing substrate, a visible light diffusing layer disposed on the firstglazing substrate, and a light redirecting layer adjacent to the visiblelight diffusing layer, where the visible light diffusing layer and lightredirecting layer are oriented such that incoming solar light contactsthe visible light diffusing layer before contacting the lightredirecting layer are illustrated in FIGS. 4-6.

In FIG. 4, hybrid construction 400 comprises first glazing substrate410, visible light diffusing layer 420 disposed on first glazingsubstrate 410, and light redirecting layer 430. This construction isconfigured such that incoming solar light contacts first glazingsubstrate 410 first, passes through consecutively first glazingsubstrate 410 and visible light diffusing layer 420 before contactinglight redirecting layer 430 and being directed upwards. Visible lightdiffusing layer 420 and light redirecting layer 430 can be separatelayers or can be a composite light diffusing and redirectingconstruction, such as a film. In some embodiments, layers of opticallyclear adhesive can be used to adhere visible light diffusing layer 420to first glazing substrate 410 (not shown) and/or to adhere lightredirecting layer 430 to visible light diffusing layer 420 (not shown).As described above, visible light diffusing layer 420 may be a film orcoating, a textured surface or topography on first glazing substrate410, or a visible light diffusing substrate.

In FIG. 5, hybrid construction 500 comprises first glazing substrate510, visible light diffusing layer 520 disposed on first glazingsubstrate 510, and light redirecting layer 530. This construction isconfigured such that incoming solar light contacts visible lightdiffusing layer 520 first, passes through consecutively visible lightdiffusing layer 520 and first glazing substrate 510 before contactinglight redirecting layer 530 and being directed upwards. In someembodiments, layers of optically clear adhesive can be used to adherevisible light diffusing layer 520 to first glazing substrate 510 (notshown) and/or to adhere light redirecting layer 530 to first glazingsubstrate 510 (not shown). As described above, visible light diffusinglayer 520 may be a film or coating, a textured surface or topography onfirst glazing substrate 510, or a visible light diffusing substrate.

In FIG. 6, hybrid construction 600 comprises first glazing substrate610, visible light diffusing layer 620 disposed on first glazingsubstrate 610, light redirecting layer 630, and second glazing substrate640. This construction is configured such that incoming solar lightcontacts first glazing substrate 610 first, passes through consecutivelyfirst glazing substrate 610 and visible light diffusing layer 620 beforecontacting light redirecting layer 630 and being directed upwards.Visible light diffusing layer 620 and light redirecting layer 630 can beseparate layers or can be a composite light diffusing and redirectingconstruction, such as a film. In some embodiments, layers of opticallyclear adhesive can be used to adhere visible light diffusing layer 620to first glazing substrate 610 (not shown) and/or to adhere lightredirecting layer 630 to visible light diffusing layer 620 and/or secondglazing substrate 640 (not shown). As described above, visible lightdiffusing layer 620 may be a film or coating, a textured surface ortopography on first glazing substrate 610, or a visible light diffusingsubstrate. In some embodiments, a void space (not shown) may be presentbetween light redirecting layer 630 and second glazing substrate 640.This void space may be a vacuum space or may be filled with, for exampleair or other gas.

In other embodiments of this disclosure, the hybrid constructioncomprises a first glazing substrate, a patterned visible light diffusinglayer, and a light redirecting layer adjacent to the visible lightdiffusing layer. The patterned visible light diffusing layer and lightredirecting layer adjacent to the visible light diffusing layer maycomprise a composite light redirection construction such as a film, orthey may be separate layers. The light diffusing layer and the lightredirecting layer may be in any orientation to the glazing substrate.The use of a patterned visible light diffusing layer provides theadvantageous properties described above, coupled with the need to usefewer diffusive elements. This not only can assist in making themanufacturing less expensive, it can be aesthetically more appealing tohave less of the window surface diffusive to visible light. For example,with a home or office window a viewer that looks through a visible lightdiffusing element will generally have a hazy view instead of the desiredbright exterior view.

In some embodiments, the patterned visible light diffusing layer isdisposed on the first glazing substrate. A wide variety of patternedlight diffusing layers are suitable. In some embodiments, the patternedlight diffusing layer comprises a patterned light diffusing film orcoating that is attached to the first glazing substrate. In otherembodiments, the patterned light diffusing layer comprises a texturedsurface or topography capable of scattering light, present on thesurface of the first glazing substrate. In still other embodiments, thepatterned light diffusing layer comprises a patterned light diffusingsubstrate, such as a glazing substrate, that comprises a texturedsurface or topography capable of scattering light, present on thesurface of the light diffusing substrate or may contain a pattern oflight diffusing particles either within the substrate matrix, or presentas a surface coating within a cured binder matrix. In these embodiments,the light diffusing substrate is separate from the first glazingsubstrate.

The patterned visible light diffusing layer can be prepared by a varietyof methods. In some embodiments, the patterned light diffusing layercomprises a patterned film or coating attached to the first glazingsubstrate, similar to the light diffusing films and coatings describedabove. However, the light diffusing elements of these films or coatingsare patterned rather than continuous.

A film with a patterned light diffusing layer may be prepared bylaminating an optically clear film with film segments in which the filmsegments contain light diffusing elements. Additionally, a lightdiffusing coating can be applied to an optically clear film and cured togenerate a film with a patterned light diffusion layer. Another methodinvolves printing a diffusing pattern onto a film as described in, forexample, PCT Publication WO 2005/005162 (Hayashi et al.).

A coated visible light diffusing pattern can be generated by coating atleast one surface of the first glazing substrate in a pattern with alight diffusing layer such as those described above.

A variety of patterned diffusive films are commercially available. Amongthese films are those available from 3M Company, St. Paul, Minn. underthe trade designation FASARA, such as FASARA AURA 9, and FASARA LEISE.

In other embodiments, the patterned light diffusing layer comprises atextured surface or topography capable of scattering light, present onthe surface of the first glazing substrate. Surface modification of thesurface of the first glazing substrate may be carried out as describedabove, except that the modification produces a patterned surface layerinstead of a continuous modified surface layer.

In some embodiments, the patterned light diffusing layer is disposed onthe light redirecting layer instead of the first glazing substrate. Inthese embodiments the light diffusing layer can be a film or coating andis applied to the light redirecting layer using the techniques describedabove.

As mentioned above, in some embodiments, the patterned light diffusinglayer and the light redirecting layer form a composite light redirectionconstruction. Such a composite construction has been described above. Inthese embodiments, however, the composite construction can be inconfigurations such that incoming solar light contacts either the lightdiffusing layer or the light redirecting layer first.

Some specific embodiments of hybrid constructions comprising a firstglazing substrate, a patterned visible light diffusing layer, and alight redirecting layer adjacent to the visible light diffusing layerare illustrated in FIGS. 7-8.

In FIG. 7, hybrid construction 700 comprises first glazing substrate710, patterned visible light diffusing layer 720 disposed on firstglazing substrate 710, and light redirecting layer 730. In FIG. 7 lightredirecting layer 730 is also shown to be patterned, but such patterningis optional. This construction is configured such that incoming solarlight may contact first glazing substrate 710 first, or it may contactlight redirecting layer 730 first. Visible light diffusing layer 720 andlight redirecting layer 730 can be separate layers or can be a compositelight diffusing and redirecting construction, such as a film. In someembodiments, layers of optically clear adhesive can be used to adherevisible light diffusing layer 720 to first glazing substrate 710 (notshown) and/or to adhere light redirecting layer 730 to visible lightdiffusing layer 720 (not shown). As described above, patterned visiblelight diffusing layer 720 may be a film or coating, a textured surfaceor topography on first glazing substrate 410, or a patterned visiblelight diffusing substrate. Patterned light diffusing layer 720 may be acontinuous layer as shown in FIG. 7, or the light diffusing elements maybe discrete.

In FIG. 8, hybrid construction 800 comprises first glazing substrate810, patterned visible light diffusing layer 820 disposed on firstglazing substrate 810, and light redirecting layer 830. In FIG. 8 lightredirecting layer 830 is also shown to be patterned, but such patterningis optional. This construction is configured such that incoming solarlight may contact patterned light diffusing layer 820 first, or it maycontact light redirecting layer 830 first. In some embodiments, layersof optically clear adhesive can be used to adhere visible lightdiffusing layer 820 to first glazing substrate 810 (not shown) and/or toadhere light redirecting layer 830 to first glazing substrate 810 (notshown). As described above, patterned visible light diffusing layer 820may be a film or coating, a textured surface or topography on firstglazing substrate 810, or a patterned visible light diffusing substrate.Patterned light diffusing layer 820 may be a continuous layer as shownin FIG. 8, or the light diffusing elements may be discrete.

Similarly to the above described embodiments, embodiments that comprisea patterned light diffusing layer and a light redirecting layer maycomprise additional optional layers or substrates as described above,and can be adhered through the use of adhesive layers as describedabove. Additionally, the light redirecting layer may also be patterned.The pattern of the light redirecting layer may match the pattern of thelight diffusing layer, or the pattern may be different.

The pattern of the light diffusing layer can be any suitable pattern.Examples of suitable patterns include diffusive stripes, regulargeometric shapes, or irregular geometric shapes. The diffusive stripes,regular geometric shapes, or irregular geometric shapes may be in theform of straight lines, curvy lines, diagonal lines, discontinuouslines, circles, polygons, and the like. For ease of manufacture,straight lines are particularly useful.

In still other embodiments of this disclosure, the hybrid constructioncomprises at least two glazing substrates with the diffusive layer andlight redirecting layer each disposed on one of the glazing substrates.In these embodiments, regardless of the relative orientation of thediffusive layer and the light redirecting layer, an intervening space ispresent between the diffusive layer and the light redirecting layer.This intervening space can be a vacuum, as is common in some glazingconstructions or the space may contain air or other gas such as nitrogenor argon, for example.

Suitable light diffusing layers and light redirecting layers aredescribed above. In these embodiments, a wide variety of configurationsof the light diffusing layer and light redirecting layer are possible.For example, either the light diffusing layer or the light redirectinglayer can be disposed on the first glazing substrate. The first glazingsubstrate is the one that is on the “outside” of the glazing article(i.e. facing the outside environment and therefore incoming solar lightcontacts this substrate first. Also, the light diffusing layer or thelight redirecting layer can be disposed on either major surface of thefirst glazing substrate. The first glazing substrate has two majorsurfaces, one that face the outside environment and one that faces thesecond glazing substrate. Similarly, the companion layer that isdisposed on the second glazing substrate can be disposed on either majorsurface of the second glazing substrate. The two major surfaces of thesecond glazing substrate are the surface that faces the interior of theroom and the surface that faces the first glazing substrate.

In some embodiments, the light diffusing layer and the light redirectinglayer are disposed on the glazing substrates such that the layers arefacing each other. In this way, both of the layers face the interveningspace and are not exposed to either the outside environment or theinterior room environment. This configuration can protect the layersfrom scratching, abrasion, weathering, soiling and similar conditions.

Some specific embodiments of hybrid constructions comprising at leasttwo glazing substrates with the diffusive layer and light redirectinglayer each disposed on one of the glazing substrates with an interveningspace present between the diffusive layer and the light redirectinglayer, are illustrated in FIGS. 9-12.

In FIG. 9, hybrid construction 900 comprises first glazing substrate 910and second glazing substrate 940, visible light diffusing layer 920disposed on first glazing substrate 910, light redirecting layer 930disposed on second glazing substrate 940, and intervening space 960between visible light diffusing layer 920 and light redirecting layer930. This construction is configured such that incoming solar light maycontact either first glazing substrate 910 or second glazing substrate940 first. In some embodiments, layers of optically clear adhesive canbe used to adhere visible light diffusing layer 920 to first glazingsubstrate 910 (not shown) and/or to adhere light redirecting layer 930to second glazing substrate 940 (not shown). As described above, visiblelight diffusing layer 920 may be a film or coating, a textured surfaceor topography on first glazing substrate 910, or a visible lightdiffusing substrate. The intervening space 960 may be a vacuum space ormay be filled with, for example air or other gas. To isolate interveningspace 960 from the external environment, optional sealing members 950may be used.

In FIG. 10, hybrid construction 1000 comprises first glazing substrate1010 and second glazing substrate 1040, visible light diffusing layer1020 disposed on first glazing substrate 1010, light redirecting layer1030 disposed on second glazing substrate 1040, and intervening space1060 between first glazing substrate 1010 and light redirecting layer1030. This construction is configured such that incoming solar light maycontact either light diffusing layer 1020 or second glazing substrate1040 first. In some embodiments, layers of optically clear adhesive canbe used to adhere visible light diffusing layer 1020 to first glazingsubstrate 1010 (not shown) and/or to adhere light redirecting layer 1030to second glazing substrate 1040 (not shown). As described above,visible light diffusing layer 1020 may be a film or coating, a texturedsurface or topography on first glazing substrate 1010, or a visiblelight diffusing substrate. The intervening space 1060 may be a vacuumspace or may be filled with, for example air or other gas. To isolateintervening space 1060 from the external environment, optional sealingmembers 1050 may be used.

In FIG. 11, hybrid construction 1100 comprises first glazing substrate1110 and second glazing substrate 1140, visible light diffusing layer1120 disposed on first glazing substrate 1110, light redirecting layer1130 disposed on second glazing substrate 1140, and intervening space1160 between visible light diffusing layer 1120 and second glazingsubstrate 1140. This construction is configured such that incoming solarlight may contact either first glazing substrate 1110 or lightredirecting layer 1130 first. In some embodiments, layers of opticallyclear adhesive can be used to adhere visible light diffusing layer 1120to first glazing substrate 1110 (not shown) and/or to adhere lightredirecting layer 1130 to second glazing substrate 1140 (not shown). Asdescribed above, visible light diffusing layer 1120 may be a film orcoating, a textured surface or topography on first glazing substrate1110, or a visible light diffusing substrate. The intervening space 1160may be a vacuum space or may be filled with, for example air or othergas. To isolate intervening space 1160 from the external environment,optional sealing members 1150 may be used.

In FIG. 12, hybrid construction 1200 comprises first glazing substrate1210 and second glazing substrate 1240, visible light diffusing layer1220 disposed on first glazing substrate 1210, light redirecting layer1230 disposed on second glazing substrate 1240, and intervening space1260 between first glazing substrate 1210 and second glazing substrate1240. This construction is configured such that incoming solar light maycontact either visible light diffusing layer 1220 or light redirectinglayer 1230 first. In some embodiments, layers of optically clearadhesive can be used to adhere visible light diffusing layer 1220 tofirst glazing substrate 1210 (not shown) and/or to adhere lightredirecting layer 1230 to second glazing substrate 1240 (not shown). Asdescribed above, visible light diffusing layer 1220 may be a film orcoating, a textured surface or topography on first glazing substrate1210, or a visible light diffusing substrate. The intervening space 1260may be a vacuum space or may be filled with, for example air or othergas. To isolate intervening space 1260 from the external environment,optional sealing members 1250 may be used.

As with the other embodiments described above, these hybridconstructions can also contain additional optional layers andsubstrates, as long as these layers and substrates do not interfere withthe light redirection and diffusion properties of the hybridconstructions. Suitable optional layers and substrates have beendescribed above.

This disclosure includes the following embodiments.

Among the embodiments are solar light redirecting glazing units. A firstembodiment includes a solar light redirecting glazing unit, comprising:a first glazing substrate; a visible light diffusing layer disposed onthe first glazing substrate; and a light redirecting layer adjacent tothe visible light diffusing layer, the light redirecting layercomprising a major surface forming a plurality of prism structures, andwherein the visible light diffusing layer and light redirecting layerare oriented such that incoming solar light contacts the visible lightdiffusing layer before contacting the light redirecting layer.

Embodiment 2 is the solar light redirecting glazing unit of embodiment1, wherein the visible light diffusing layer comprises a visible lightdiffusing film or a visible light diffusing glazing substrate.

Embodiment 3 is the solar light redirecting glazing unit of embodiment 1or 2, wherein the visible light diffusing layer and the lightredirecting layer are attached to each other to form a solar lightredirecting construction.

Embodiment 4 is the solar light redirecting glazing unit of any ofembodiments 1-3, wherein the visible light diffusing layer and the lightredirecting layer comprise polymeric films.

Embodiment 5 is the solar light redirecting glazing unit of any ofembodiments 1-4, wherein the first glazing substrate has a surface areavalue and the solar light redirecting construction is disposed on only aportion of the surface area value.

Embodiment 6 is the solar light redirecting glazing unit of any ofembodiments 1-5, wherein the plurality of prism structures comprises aplurality of asymmetric prisms.

Embodiment 7 is the solar light redirecting glazing unit of any ofembodiments 1-6, wherein the visible light diffusing layer comprises apatterned light diffusing layer.

Embodiment 8 is the solar light redirecting glazing unit of any ofembodiments 1-7, wherein the light redirecting layer comprises apatterned light redirecting layer.

Embodiment 9 is the solar light redirecting glazing unit of any ofembodiments 1-8, further comprising at least one additional layer.

Embodiment 10 is the solar light redirecting glazing unit of embodiment9, wherein the at least one additional layer comprises a low E layer, aninfrared light rejecting layer, a color or tinting layer, or combinationthereof.

Embodiment 11 is the solar light redirecting glazing unit of embodiment10, wherein the infrared light rejecting layer comprises an infraredlight rejecting multi-layer film, an infrared light rejecting coating,or combination thereof.

Embodiment 12 is the solar light redirecting glazing unit of embodiment11, wherein the infrared light rejecting layer reflects infrared light,absorbs infrared light, or combination thereof.

Embodiment 13 is the solar light redirecting glazing unit of any ofembodiments 1-12, further comprising at least one additional glazingsubstrate.

Embodiment 14 is the solar light redirecting glazing unit of any ofembodiments 1-13, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 50%.

Embodiment 15 is the solar light redirecting glazing unit of any ofembodiments 1-14, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 60%.

Embodiment 16 is the solar light redirecting glazing unit of any ofembodiments 1-15, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 70%.

Embodiment 17 is the solar light redirecting glazing unit of any ofembodiments 1-16, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 80%.

Embodiment 18 is the solar light redirecting glazing unit of any ofembodiments 1-17, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 85%.

Embodiment 19 is the solar light redirecting glazing unit of any ofembodiments 1-18, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 90%.

Embodiment 20 is the solar light redirecting glazing unit of any ofembodiments 1-19, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 95%.

Embodiment 21 is the solar light redirecting glazing unit of any ofembodiments 1-20, wherein the haze of the solar light redirectingglazing unit is at least 10%.

Embodiment 22 is the solar light redirecting glazing unit of any ofembodiments 1-21, wherein the haze of the solar light redirectingglazing unit is at least 15%.

Embodiment 23 is the solar light redirecting glazing unit of any ofembodiments 1-22, wherein the haze of the solar light redirectingglazing unit is at least 20%.

Embodiment 24 is the solar light redirecting glazing unit of any ofembodiments 1-23, wherein the haze of the solar light redirectingglazing unit is at least 30%.

Embodiment 25 is the solar light redirecting glazing unit of any ofembodiments 1-24, wherein the haze of the solar light redirectingglazing unit is at least 40%.

Embodiment 26 is the solar light redirecting glazing unit of any ofembodiments 1-25, wherein the clarity of the solar light redirectingglazing unit is in the range of 10-99%.

Embodiment 27 includes a solar light redirecting glazing unit,comprising: a first glazing substrate; a patterned visible lightdiffusing layer; and a light redirecting layer adjacent to the visiblelight diffusing layer wherein the light redirecting layer comprising amajor surface forming a plurality of prism structures.

Embodiment 28 is the solar light redirecting glazing unit of embodiment27, wherein the patterned visible light diffusing layer and the lightredirecting layer adjacent to the visible light diffusing layer form acomposite construction.

Embodiment 29 is the solar light redirecting glazing unit of embodiment27 or 28, wherein the patterned visible light diffusing layer comprisesa patterned visible light diffusing film or patterned visible lightdiffusing glazing substrate.

Embodiment 30 is the solar light redirecting glazing unit of any ofembodiments 27-29, wherein the patterned visible light diffusing filmcomprises a film with diffusive stripes, regular geometric shapes, orirregular geometric shapes.

Embodiment 31 is the solar light redirecting glazing unit of any ofembodiments 27-30, wherein the patterned visible light diffusing layerand the light redirecting layer adjacent to the visible light diffusinglayer are arranged such that incoming solar light contacts the lightredirecting layer before contacting the visible light diffusing layer.

Embodiment 32 is the solar light redirecting glazing unit of any ofembodiments 27-30, wherein the patterned visible light diffusing layerand the light redirecting layer adjacent to the visible light diffusinglayer are arranged such that incoming solar light contacts the visiblelight diffusing layer before contacting the light redirecting layer.

Embodiment 33 is the solar light redirecting glazing unit of any ofembodiments 27-32, wherein the plurality of prism structures comprises aplurality of asymmetric prisms.

Embodiment 34 is the solar light redirecting glazing unit of any ofembodiments 27-33, further comprising at least one additional layer.

Embodiment 35 is the solar light redirecting glazing unit of embodiment34, wherein the at least one additional layer comprises a low E layer,an infrared light rejecting layer, a color or tinting layer, orcombination thereof.

Embodiment 36 is the solar light redirecting glazing unit of embodiment35, wherein the infrared light rejecting layer comprises an infraredlight rejecting multi-layer film, an infrared light rejecting coating,or combination thereof.

Embodiment 37 is the solar light redirecting glazing unit of embodiment36, wherein the infrared light rejecting layer reflects infrared light,absorbs infrared light, or combination thereof.

Embodiment 38 is the solar light redirecting glazing unit of any ofembodiments 27-37, further comprising at least one additional glazingsubstrate.

Embodiment 39 is the solar light redirecting glazing unit of any ofembodiments 27-38, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 50%.

Embodiment 40 is the solar light redirecting glazing unit of any ofembodiments 27-39, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 60%.

Embodiment 41 is the solar light redirecting glazing unit of any ofembodiments 27-40, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 70%.

Embodiment 42 is the solar light redirecting glazing unit of any ofembodiments 27-41, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 80%.

Embodiment 43 is the solar light redirecting glazing unit of any ofembodiments 27-42, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 85%.

Embodiment 44 is the solar light redirecting glazing unit of any ofembodiments 27-43, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 90%.

Embodiment 45 is the solar light redirecting glazing unit of any ofembodiments 27-44, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 95%.

Embodiment 46 is the solar light redirecting glazing unit of any ofembodiments 27-45, wherein the haze of the solar light redirectingglazing unit is at least 10%.

Embodiment 47 is the solar light redirecting glazing unit of any ofembodiments 27-46, wherein the haze of the solar light redirectingglazing unit is at least 15%.

Embodiment 48 is the solar light redirecting glazing unit of any ofembodiments 27-47, wherein the haze of the solar light redirectingglazing unit is at least 20%.

Embodiment 49 is the solar light redirecting glazing unit of any ofembodiments 27-48, wherein the haze of the solar light redirectingglazing unit is at least 30%.

Embodiment 50 is the solar light redirecting glazing unit of any ofembodiments 27-49, wherein the haze of the solar light redirectingglazing unit is at least 40%.

Embodiment 51 is the solar light redirecting glazing unit of any ofembodiments 27-50, wherein the clarity of the solar light redirectingglazing unit is in the range of 10-99%.

Embodiment 52 includes a solar light redirecting glazing unit,comprising: a first glazing substrate comprising a first major surfaceand a second major surface; a solar light redirecting layer disposed onthe first major surface of the first glazing substrate, the solar lightredirecting layer comprising a major surface forming a plurality ofprism structures; a second glazing substrate comprising a first majorsurface and a second major surface; a visible light diffusing layerdisposed on the first major surface of the second glazing substrate: andan intervening space between the solar light redirecting layer and thevisible light diffusing layer.

Embodiment 53 is the solar light redirecting glazing unit of embodiment52, wherein the first major surface of the first glazing substrate isdirected towards the first major surface of the second glazingsubstrate.

Embodiment 54 is the solar light redirecting glazing unit of embodiment52 or 53, wherein the glazing unit is arranged such that incoming solarlight contacts the visible light diffusing layer before contacting thelight redirecting layer.

Embodiment 55 is the solar light redirecting glazing unit of any ofembodiments 52-53, wherein the glazing unit is arranged such thatincoming solar light contacts the light redirecting layer beforecontacting the visible light diffusing layer.

Embodiment 56 is the solar light redirecting glazing unit of any ofembodiments 52-55, wherein the first major surface of the first glazingsubstrate is directed away from the first major surface of the secondglazing substrate.

Embodiment 57 is the solar light redirecting glazing unit of any ofembodiments 52-56, wherein the plurality of prism structures comprises aplurality of asymmetric prisms.

Embodiment 58 is the solar light redirecting glazing unit of any ofembodiments 52-57, further comprising at least one additional layer.

Embodiment 59 is the solar light redirecting glazing unit of embodiment58, wherein the at least one additional layer comprises a low E layer,an infrared light rejecting layer, a color or tinting layer, orcombination thereof.

Embodiment 60 is the solar light redirecting glazing unit of embodiment59, wherein the infrared light rejecting layer comprises an infraredlight rejecting multi-layer film, an infrared light rejecting coating,or combination thereof.

Embodiment 61 is the solar light redirecting glazing unit of embodiment60, wherein the infrared light rejecting layer reflects infrared light,absorbs infrared light, or combination thereof.

Embodiment 62 is the solar light redirecting glazing unit of any ofembodiments 52-61, further comprising at least one additional glazingsubstrate.

Embodiment 63 is the solar light redirecting glazing unit of any ofembodiments 52-62, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 50%.

Embodiment 64 is the solar light redirecting glazing unit of any ofembodiments 52-63, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 60%.

Embodiment 65 is the solar light redirecting glazing unit of any ofembodiments 52-64, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 70%.

Embodiment 66 is the solar light redirecting glazing unit of any ofembodiments 52-65, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 80%.

Embodiment 67 is the solar light redirecting glazing unit of any ofembodiments 52-66, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 85%.

Embodiment 68 is the solar light redirecting glazing unit of any ofembodiments 52-67, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 90%.

Embodiment 69 is the solar light redirecting glazing unit of any ofembodiments 52-68, wherein the visible light transmission (% T) of thesolar light redirecting glazing unit is at least 95%.

Embodiment 70 is the solar light redirecting glazing unit of any ofembodiments 52-69, wherein the haze of the solar light redirectingglazing unit is at least 10%.

Embodiment 71 is the solar light redirecting glazing unit of any ofembodiments 52-70, wherein the haze of the solar light redirectingglazing unit is at least 15%.

Embodiment 71 is the solar light redirecting glazing unit of any ofembodiments 52-70, wherein the haze of the solar light redirectingglazing unit is at least 20%.

Embodiment 72 is the solar light redirecting glazing unit of any ofembodiments 52-71, wherein the haze of the solar light redirectingglazing unit is at least 30%.

Embodiment 73 is the solar light redirecting glazing unit of any ofembodiments 52-72, wherein the haze of the solar light redirectingglazing unit is at least 40%.

Embodiment 74 is the solar light redirecting glazing unit of any ofembodiments 52-73, wherein the clarity of the solar light redirectingglazing unit is in the range of 10-99%.

EXAMPLES

These examples are merely for illustrative purposes only and are notmeant to be limiting on the scope of the appended claims. All parts,percentages, ratios, etc. in the examples and the rest of thespecification are by weight, unless noted otherwise. The followingabbreviations are used herein: cm=centimeter; in=inch; mm=millimeter.Solvents and other reagents used were obtained from Sigma-AldrichChemical Company; Milwaukee, Wis. unless otherwise noted.

Optical Measurements

Transmission, haze and clarity of the specimens were measured using a“HAZE-GARD PLUS” (BYK-Gardner, Columbia, Md.) according to test methodASTM D1003.

BTDF (bi-directional transmission distribution function) was measuredusing a commercially available “IS-SA” imaging sphere system fromRadiant Imaging, Redmond, Wash. BTDF was measured with an incident angleof 60 degrees elevation. BTDF for deflection up was measured at thebrightest angle as indicated in Table 2 which varies slightly fromsample to sample due to glass alignment and normal measurementvariation.

Preparation of Structured Light Redirecting Layer

A master tool having the negative of the desired linear grooves andprismatic elements (with a cross section similar to FIG. 1) was obtainedusing a diamond turning process. A UV curable resin composition wasprepared by blending 74 parts by weight of an aliphatic urethaneacrylate oligomor, commercially available under the trade designation“PHOTOMER 6010” from Cognis, Monheim, Germany, 25 parts 1,6-hexanedioldiacrylate, commercially available under the trade designation “SARTOMERSR 238” from Sartomer, Exton, Pa., and an alpha-hydroxy ketone UVphotoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), commerciallyavailable under the trade designation “DAROCUR 1173” from Ciba, Basel,Switzerland. A 76 micrometer (3 mil) thick PET (polyethyleneterephthalate) film, commercially available from DuPont Teijin Films,Hopewell, Va. under the trade designation “MELINEX 453”, was coated withthe UV curable resin to an approximate thickness of 85 micrometers. Thecoated film was placed in physical communication with the master toolsuch that the grooves were void of any air. The resin was cured while inphysical communication with the master tool with a microwave powered UVcuring system available from Fusion UV systems, Gaithersburg, Md. Thecured resin on the web was removed from the master tool resulting in amicrostructured film. One liner of a 25 micrometer (1 mil) thickoptically clear adhesive transfer tape, commercially available from 3MCompany, St. Paul, Minn. under the trade designation “3M OPTICALLY CLEARADHESIVE 8171”, was removed and the exposed adhesive surface waslaminated to the non-structured side of the microstrutured film in aroll-to-roll laminator available from Protech Engineering, Wilmington,Del. A multilayer film article as disclosed on pages 5-6 of US PatentPublication No. 2006/0154049 was laminated to the structured side of themicrostructured film to produce the final light redirecting filmlaminate.

Preparation of Solar Light Redirecting Glazing Unit

For Examples 1 and 2 (EX1 and EX2) and Comparative Example 1 (CE1) thefilm described under “Structured Light Redirecting Layer” was coatedwith an acrylic pressure sensitive adhesive in a web coater to obtain anapproximately 8 micrometer thick adhesive layer on the opposite side ofthe structured film. The film was applied to a 3 in square (7.6 cmsquare) clear 3 mm float glass using a roller to obtain bubble-freeapplication.

For EX1 and EX2 respectively, “3M FASARA DESIGN FILM SH2EM LAUSENNE” and“3M FASARA DESIGN FILM SH2CH MAT CRYSTAL i” architectural decoratingfilms commercially available from 3M Company, St. Paul, Minn. wereapplied to a second piece of 3 inch square (7.6 cm square) 3 mm floatglass. CE1 had no diffusing film applied but instead used plain 3 mmplate glass as the second pane.

For EX1 and EX2 “3M DOUBLE SIDED FOAM TAPE 4408”, commercially availablefrom 3M Company, St. Paul, Minn., was applied along the four sides ofthe glass specimen with the diffusing film for EX1 and EX2 and the plainplate glass for CE1. The previously prepared glass sample havingstructured film was adhered on the vinyl tape to obtain the double panestructure of FIG. 9 for EX1 and EX2. CE1 was missing the diffusing film620 of FIG. 9.

Haze, clarity, % transmission (% T) and BTDF were measured as describedunder “Optical Measurements” and are shown in Tables 1. Measurementswere made with the light source on the daylighting film side. Lower BTDFdeflection down indicates reduced glare.

TABLE 1 % T Haze Clarity BTDF deflection up BTDF deflection down EX1 8840 54 12.37 (at 44.8 degree up)  1.52 (at 18.7 degree down) EX2 89 56 19 3.0 (at 46.2 degree up)  0.7 (at 18.7 degree down) CE1 92 1 99.5 83.7(at 45.2 degree up) 4.94 (at 18.7 degree down)

What is claimed is:
 1. A solar light redirecting glazing unit,comprising: a first glazing substrate; a visible light diffusing layerdisposed on the first glazing substrate; and a light redirecting layeradjacent to the visible light diffusing layer, the light redirectinglayer comprising a major surface forming an ordered arrangement of aplurality of prism structures, and wherein the visible light diffusinglayer and light redirecting layer are oriented such that incoming solarlight contacts the visible light diffusing layer before contacting thelight redirecting layer.
 2. The solar light redirecting glazing unit ofclaim 1, wherein the visible light diffusing layer comprises a visiblelight diffusing film or a visible light diffusing glazing substrate. 3.The solar light redirecting glazing unit of claim 1, wherein the visiblelight diffusing layer and the light redirecting layer are attached toeach other to form a solar light redirecting construction.
 4. The solarlight redirecting glazing unit of claim 3, wherein the visible lightdiffusing layer and the light redirecting layer comprise polymericfilms.
 5. The solar light redirecting glazing unit of claim 3, whereinthe first glazing substrate has a surface area value and the solar lightredirecting construction is disposed on only a portion of the surfacearea value.
 6. The solar light redirecting glazing unit of claim 1,wherein the plurality of prism structures comprises a plurality ofasymmetric prisms.
 7. A solar light redirecting glazing unit,comprising: a first glazing substrate; a patterned visible lightdiffusing layer; and a light redirecting layer adjacent to the visiblelight diffusing layer wherein the light redirecting layer comprising amajor surface forming an ordered arrangement of a plurality of prismstructures.
 8. The solar light redirecting glazing unit according toclaim 7, wherein the patterned visible light diffusing layer and thelight redirecting layer adjacent to the visible light diffusing layerform a composite construction.
 9. The solar light redirecting glazingunit according to claim 7, wherein the patterned visible light diffusinglayer comprises a patterned visible light diffusing film or patternedvisible light diffusing glazing substrate.
 10. The solar lightredirecting glazing unit according to claim 9, wherein the patternedvisible light diffusing film comprises a film with diffusive stripes,regular geometric shapes, or irregular geometric shapes.
 11. The solarlight redirecting glazing unit according to claim 7, wherein thepatterned visible light diffusing layer and the light redirecting layeradjacent to the visible light diffusing layer are arranged such thatincoming solar light contacts the light redirecting layer beforecontacting the visible light diffusing layer.
 12. The solar lightredirecting glazing unit according to claim 7, wherein the patternedvisible light diffusing layer and the light redirecting layer adjacentto the visible light diffusing layer are arranged such that incomingsolar light contacts the visible light diffusing layer before contactingthe light redirecting layer.
 13. The solar light redirecting glazingunit according to claim 7, further comprising additional layers.
 14. Thesolar light redirecting glazing unit of claim 7, wherein the pluralityof prism structures comprises a plurality of asymmetric prisms.